So the way this works is that there are two cameras on the top of the LED cab sign. They each are pointing out to the street and feeding video into beautiful LED signs that output the video as the cabs are driving by.

So its low-res imaging coming back, but that makes it beautiful. As you get in
the cab you see the shape of your head and face and as it drives by you watch the chip trying to process that type of speed and settling in as it reaches a stop light.

I like the basic idea. It's something I'd want to fool with a bunch before I was sure whether I wanted to go so low resolution. You may have seen those clear plastic domes that display caller ID info. They are sorta striking. I might use them instead of the led desplay you've suggested. I could be wrong. I think yours is an idea worthy of foolin' with.